Noma Domezweni has been cast in the role in the spin-off play and Emma, who played Hermione in the movies, says she can't wait to see Noma take to the stage.

She tweeted: ''Can't wait to see Noma Dumezweni as Hermione on stage this year. #harrypotterandthecursedchild #2016 (sic).''

Emma's tweet comes after 'Harry Potter' author J.K. Rowling defended the casting of a black actress in the role.

The author insisted she ''never specified'' the ethnicity of the popular witch when writing her series of books, so can't understand why some people are outraged that Noma will take on the role.

She tweeted: ''Canon: brown eyes, frizzy hair and very clever. White skin was never specified. Rowling loves black Hermione (sic)''

She added: ''I'm so excited with the choice of casting for Harry Potter and the Cursed Child. I can't wait to see Jamie [Parker], Noma and Paul [Thornley] bring the adult Harry, Hermione and Ron to life on stage next summer.''

The two-part play is due to make its debut at the Palace Theatre in the heart of London in summer 2016.

In the movies Harry, Hermione and Ron were played by Daniel Radcliffe, Emma and Rupert Grint.